CHARACTERIZATION OF MILK COAGULATION ABILITY IN BULK MILK SAMPLES Valentina Toffanin, Massimo De Marchi, Mauro Penasa, Denis Pretto, Martino Cassandro 20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

Introduction At the global level there is a growth in production and consumption of cheese At present, 70% of the available milk in Italy is used for cheese production and about 35% is transformed into PDO products (Pieri, 2011). As reported by Pretto et al. (2012), Cassandro et al. (2008) and Summer et al. (2002), basic requirements for cheese-making are milk coagulation properties (MCP) 20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

RCT k20 a30 What is MCP ? milk + rennet minutes 30 minutes RCT Rennet Clotting Time (min) k20 Curd Firming Time (min) 20mm a30 Curd Firmness (mm) 20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

Sources of variation for MCP Herd & breed [De Marchi et al. (2007), Tyrisevä et al. (2002) and Mariani et al. (2002, 1997)] Season [Barlowska et al. (2012), Chládek et al. (2011), Jõudu et al. (2008) and De Marchi et al. (2007)] Chemical composition [Protein & Casein: Jõudu et al. (2008). Somatic Cell Count: Politis and Ng-Kwai-Hang (1988) and Okigbo et al. (1985b). Titratable acidity & pH: Formaggioni et al. (2001) and Okigbo et al. (1985a)] 20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

Aim To investigate dairy cooperative, herd, season and milk quality and acidity traits on MCP (RCT, k20, a30) in bulk samples 20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

Material & Methods 20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

Material and methods / milk analyses 1,570 bulk milk samples, June ‘08 – November ‘09, 436 dairy herds, 4 dairy cooperatives MilkoScan 6000 for fat, protein, casein contents Cell Fossomatic for Somatic cell content (SCC) Crison Compact D for pH, titratable acidity (TA) Computerized renneting meter for RCT, k20, a30 (according to the methodology of Cassandro et al., 2008) 20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

Material and methods / statistical analyses GLM procedure of SAS: ANOVA on MCP Linear model: Y : RCT, k20, a30 X : dairy cooperative, herd (dairy cooperative), year of sampling, season of sampling, classes of casein, fat, titratable acidity, somatic cell count, bacterial count 20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

Results and discussion k20, min RCT, min N Mean S.D. Skewness Curtosi RCT 1508 18.83 3.68 0.08 0.33 k20 1193 6.85 1.92 0.35 0.25 a30 26.97 8.12 -0.18 0.15 a30, mm 20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

Results and discussion Results from ANOVA for milk coagulation properties of bulk milk samples. RCT1, min k202, min a303, mm Effect F P-value Dairy cooperative4 25.03 <0.001 9.36 25.57 Herd (within dairy cooperative) 1.86 1.57 1.83 Year of sampling 19.08 1.12 0.290 0.07 0.797 Season of sampling 13.75 2.66 0.047 1.51 0.211 Casein, % 0.71 0.585 4.84 0.001 5.88 Fat, % 0.58 0.676 1.06 0.376 1.47 0.209 Titratable acidity, °SH/50mL 14.31 4.78 13.63 Somatic cell count, cells/mL 2.31 0.056 1.13 0.339 0.97 0.422 Bacterial count, cells/mL 2.48 0.042 1.70 0.148 1.56 0.183 R2 0.52 RMSE5 3.03 1.65 6.72 1RCT = rennet coagulation time; 2k20 = curd-firming time; 3a30 = curd firmness. 4Tested on herd within dairy cooperative variance. 5RMSE = root mean square error. 20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

Results and discussion Least square means of dairy effect on milk coagulation traits. RCT = rennet coagulation time (min); k20 = curd-firming time (min); a30 = curd firmness 30 minutes after rennet addition (mm). a b b ab b b 20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

Results and discussion Effect of season of sampling on RCT and k20. RCT = rennet coagulation time (min); k20 = curd-firming time (min); a30 = curd firmness 30 minutes after rennet addition (mm). 20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

Results and discussion Least squares means of rennet coagulation time (RCT, min) across classes of (a) titratable acidity and (b) somatic cell count. Titratable acidity (°SH/50mL): C1 < 3.00; C2 3.00 to 3.20; C3 3.20 to 3.40; C4 3.40 to 3.60; C5 > 3.60. Somatic cell count: C1 < 100,000; C2 100,000 to 200,000; C3 200,000 to 300,000; C4 300,000 to 400,000; C5 > 400,000. 20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

Results and discussion Least squares means of curd-firming time (k20, min) across classes of (a) casein content and (b) titratable acidity. Casein content: C1 < 2.37; C2 2.37 to 2.52; C3 2.52 to 2.67; C4 2.67 to 2.82; C5 > 2.82. Titratable acidity (°SH/50mL): C1 < 3.00; C2 3.00 to 3.20; C3 3.20 to 3.40; C4 3.40 to 3.60; C5 > 3.60. 20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

Results and discussion Least squares means of curd firmness (a30, mm) across classes of (a) casein content and (b) titratable acidity. Casein content: C1 < 2.37; C2 2.37 to 2.52; C3 2.52 to 2.67; C4 2.67 to 2.82; C5 > 2.82. Titratable acidity (°SH/50mL): C1 < 3.00; C2 3.00 to 3.20; C3 3.20 to 3.40; C4 3.40 to 3.60; C5 > 3.60. 20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

Conclusions 20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

Summarizing Favorable MCP Effect summer n. s. + - Perspectives: <RCT <k20 >a30 Season summer n. s. Casein + TA SCC - Perspectives: Studying the effect of farm characteristics on MCP (e.g. herd structures, management and feeding strategies, breed composition of dairy) 20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

Thanks to Lattebusche (Busche, Italy) Latteria di Soligo (Soligo, Italy) Latterie Trevigiane (Vedelago, Italy) Latterie Vicentine (Bressanvido, Italy) Breeders Association of Veneto region (ARAV, Padova, Italy) Veneto Agricoltura (Thiene, Italy) And… YOU! 20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012